MTFCA Forum

70 mile tour coming up and one of the participants has a T without a magneto and without a generator. Any experience out there how long the battery will hold out? Will be a full day of driving with perhaps 5-7 starts with the electric starter. Assumption is a group 1 6volt battery, not new, and less than fully charged at the onset.

That would depend on the size and condition of the battery, the battery's intitial state of charge, and the condition of the starter and the engine in general. Can the car be started with the crank? If so, I'd start with the crank to avoid issues with a depleted battery while on the road. OR, obtain a separate ignition battery and run the engine on that. A new riding mower type 12 volt battery could run the ignition for a good while if it had no other loads.

“OR, obtain a separate ignition battery and run the engine on that. A new riding mower type 12 volt battery could run the ignition for a good while if it had no other loads.”





Good idea on carrying such a spare “emergency ignition” battery.

Can’t answer on the # of starts or how long that T in question for all day tour.

All I know is to expect the battery to be drawn down. Happened to me with a hand crank 1915 speedster, running only 12v battery ignition as flywheel was sans mag.

Tour around city of Memphis and my 12v car battery that was not new but charged recently ran down. Had to walk to gas station with the battery to charge it, walk back and continue the tour. A spare motorcycle battery would have been great.

Humblej wrote: ↑

Sun Sep 14, 2025 6:51 pm

70 mile tour coming up and one of the participants has a T without a magneto and without a generator. Any experience out there how long the battery will hold out? Will be a full day of driving with perhaps 5-7 starts with the electric starter. Assumption is a group 1 6volt battery, not new, and less than fully charged at the onset.

Distance is irrelevant as the coils don't take much juice. Headlights weren't mentioned and could be factor if not LED. As mentioned the starter condition is the major factor. My guess is the starter draw, 5 or 6 starts, wouldn't be an issue since a small 6volt mower battery do well.
Does anyone else have a 6volt car? bring jumper cables in any case.

In a case like the OP describes, I'd have a good, full size battery in the car dedicated to operating the starter only, especially if the car cannot be crank started. I'd have a separate battery for the ignition only, and I'd want it to be of substantial size and in good condition and fully charged. A second full size battery would be a good choice, and a riding mower type battery would be a good second choice. If the car can be started with the crank, that's what I'd use, and I'd want to get a functional generator installed asap on any car I used on a tour, more especially if it lacked a working magneto or if hand cranking was out of the question for any reason.

A T will run on a near-dead battery if the ignition system is in good condition. However, it may not start using the starter if the battery is getting low on charge, since engaging the starter with a partially-discharged battery will drop the voltage severely, which is likely to render the ignition system inoperative as long as the starter is engaged. In such a case, the car would have to be hand cranked, or pushed, or jumper cables resorted to.

I didn't See where you mentioned what battery voltage your T has. If it's 12 volts, the above posts are all good. If it's 6 volts, the garden tractor batteries are not going to work. In that case, I would recommend that you find another good 6 volt battery as a backup.

A 12 volt garden tractor battery will do a good job of powering the ignition on a 6 volt T with stock ignition. It will NOT operate the starter. It would probably burn out 6 volt headlights, tail lights, and brake lights, so it would be advisable to see to it that 12 volt power could only reach the ignition. The stock T ignition will perform well on 12 volts. In my experience, batteries always underperform their ratings, and where no on board source of power other than a battery is available, problems are to be expected. A T ought to have a generator or at least a working magneto so that headlights and tail lights can be run day or night, and the battery can be kept up to full charge for starting purposes if and when needed.

How long will a T run on a 6V battery of unknown condition without a full charge?

A T with a good full size battery will run a T several days. Add electric starts = less.

I can recount a recent experience.
During a tour, on the last half of the last day, I noticed my generator wasn't. Plus I had to drive home the next day about 90 miles.
I was pretty nervous about the situation, but went ahead. Minimized starts (this T doesn't hand crank well, but can be started with a combination of hand & electric start if need be.) Made it home. 5 or 6 full re-starts for the trip home. When I got her parked I tested the electric start - Had plenty of power left for more starts. A lot of worry for nothing.

Before I recharged my mag, I used the following, small, 12v battery to buzz my coils on my hand crank 1915:
I could drive about 100 miles just using the battery to buzz the coils. I carried a spare, fully charged battery with me, and swapped it out at the end of day.

That gives me some idea.

speedytinc wrote: ↑

Mon Sep 15, 2025 11:36 am

How long will a T run on a 6V battery of unknown condition without a full charge?

If you live in my skin, one mile less then you need to go.

I don't believe in Murphy's law.
I do believe in O'Tooles law.
He states that Murphy was an optimist.

Humblej wrote: ↑

Sun Sep 14, 2025 6:51 pm

70 mile tour coming up and one of the participants has a T without a magneto and without a generator. Any experience out there how long the battery will hold out? Will be a full day of driving with perhaps 5-7 starts with the electric starter. Assumption is a group 1 6volt battery, not new, and less than fully charged at the onset.

I’ve had some experience with this kind of operation. Starting out with a decent, fully-charged battery he should be just fine.

For peace of mind have a backup plan: could be simply a 20’ tow strap in case starting becomes a problem. Or maybe swap batteries with another T if his runs out. Or four able-bodied types push-starting him after each stop to preserve his charge.

Most fellow T owners will be happy to help in one way or another. Wouldn’t you? Wouldn’t he?

Back in the day lots of T drivers set out on journeys with way worse. Worst that could happen is delayed arrival and potentially a fun story to tell!

Had a '78 Honda Civic with carb. and points that made 2-1/2 days on dead alternator, over 100 miles.
Had a '84 Reliant with first gen computer that barely made it 20 miles to the first city after the alt. suddenly died.

The problem with using the starter on the T is that the battery may never recover after the trip; but the trip may be worth it.

I ran my speedster for a couple years without a charging system.

12 volt, T starter, fuel pump, VW distributor with normal points, brake lights and a GPS. 200+ miles one day, 75 or so the next and then charge overnight. Multiple starts each day. Battery was not noticeably down before the recharge. Did this several times with no problems.